Home Laboratory #1
C. Ophardt, Elmhurst College, c. 2002
List of Chemicals for the Home Labs
Part 1: PRE-LAB: Elements and Compounds Used in Everyday Living
At home collection of lab data (5 points)
Element Inventory Table: Find examples of as many elements and compounds as possible in the entire Periodic Table. Look at the ingredient's lists on foods, drugs, and other house hold items. Baby formula has about 15 elements listed. Look for the names of the chemicals that seem to have the name of a chemical element as part of the name. There are many names which you will not recognize - simply ignore them. In other cases you may list the names of compounds and elements which you know from common knowledge such as gold and silver in jewelry.
Do NOT make duplicates in element names or symbols, but make a fairly exhaustive listing because we will use the list for several activities such as writing the formula. Each element may be listed only once, even though you may find it numerous times. Make the following
Element Inventory Table:
On the far right side for the element count, simply count how many different elements have been found, count only one example of each element. For example in water are the elements hydrogen and oxygen. In Baking Soda, the elements sodium and carbon are found. In air, nitrogen and oxygen are found, but do not list oxygen a second time, list nitrogen instead. From these three substance five elements are counted.
As a further example, look at a can of Coke or or soda. Look at the ingredients list, read various names until one seems to sound like the name of an element. There are lots of things listed which you are not expected to recognize. But one on there is phosphoric acid. This sounds like it must have phosphorus P in it. This would be the 6th element that you have found. The element count is just a tabulation of how many different elements (no duplicates) that you can find. Without working too hard you should get 30 different elements. 30-35 if you really work at it.Where to find them: Just look at ingredients lists on all kinds of products, foods cosmetics, drugs, cereal box, baby formula has about 15 elements alone listed. If you do not have enough things in the house just go hang out in the grocery and drug store to read some labels.
This element inventory listing is worth 5 points if you find 30 elements. 25 elements = 4 points; 20 elements = 3; 15 or less elements = 2.
QUES. 1: Make the following Element Inventory Table:
(It is not necessary to make a fancy table, you may just use spaces following the headings below.)
Count, Common Substance, Chemical Name, Element Name, Element Symbol
1, water, -, oxygen, O 2, water, -, hydrogen, H
Laboratory Introduction Chemical and physical properties can be used to help identify compounds in solids such as, sodium carbonate, sodium bicarbonate, sodium chloride, calcium carbonate, and sodium hydroxide. The compounds to be tested for, as well as, all the reagents used to identify them are readily available in most drugstores, supermarkets, or variety stores. The tests require no more than a few small cups, a measuring cup, an eye dropper, and a spatula or measuring spoon. Chemicals Chemical List The chemicals are all available as household products. The white solids to be used in this lab are listed in Table 1 along with their sources. These substances can be taken directly from their packages, except for the calcium carbonate which must be powdered. You will need a minimum of 3 compounds or mixtures from the list below plus 2 where online data are given (Epsom salt and baking powder). Table 1. Compound Name, Formula, Source of Compound "Pure" Compounds: Sodium chloride, NaCl, Plain table salt Sodium bicarbonate, NaHCO3, Baking soda Sodium carbonate, Na2CO3, Washing Soda Detergent e.g. Arm & Hammer Calcium carbonate, CaCO3, Calcium supplement tablets (TUMS) Sodium Aluminum dihydroxide carbonate, NaAl(OH)2CO3, ROLAIDS Sugar Mixtures: Any solid detergent Any solid antacid Experimental Procedures PART 2: Physical Properties and Changes
Combination of online and at home collection of data (6 points)
The requirement is to do five compounds total - use any 3 of the above compounds or mixtures, plus 2 compounds given online for full credit. Or do five compounds of your own. (Minus 1/2 point for each not done.)
Proc. 1: Solubility Tests: Each of the five solids is first tested for solubility in water. To perform the solubility test, use a spatula or knife tip to obtain less than an aspirin tablet sized amount of material, (too much solid will obscure the results) and place it in a small cup with about 1-2 teaspoons (5 ml) of water. Do this with all three of the solids in separate cups. Mix and stir well for several minutes to see whether the solid will dissolve, if necessary add more water. SAVE the solutions for further testing.
Try to distinguish between complete dissolving - clear solution - These are called SOLUBLE; to almost dissolved - may have a slight cloudiness left- listed as partially SOLUBLE; to lots of solid remaining, very cloudy - listed as INSOLUBLE. Dr. O, Help! Compounds that dissolve in water undergo a physical change. The chemical formula remains intact. If the water is evaporated, the original compound is recovered.
Online data for: These two count for 2 of the five required above.
Record the observation results in a table format as follows. Dr. O, Help! QUES. 2: Observation Table for Solubility Tests On the Observation Table record the observations and results of the tests. For each compound or mixture tested, record the name, and the formula (if given), any significant observations - what did you see? and results or conclusion of the test based upon the observation. Example: Aspirin; (formula not given); white solid dispersed in water, milky, some particles float; result = insoluble.
Results for five more samples: Dr. O, Help!
QUES. 3: Match definitions and examples:
Proc 2: Evaporation of a Solution: Do the following procedure on ONE of the solutions that is soluble or almost soluble, such as the salt or sugar solution. Pour the solution into a metal sauce pan and evaporate the water using the the burner on the stove. After the water has been evaporated to dryness , a residue should remain. DO NOT OVER HEAT - AS THE SUGAR MIGHT BURN. After the pan has cooled, you might try the taste test to identify this residue. Moisten your finger, touch the residue, and cautiously taste it.
QUES. 4: A physical change occurs when the composition of a substance remains the same. (True or False)
QUES. 5: A chemical change occurs when the composition of a substance remains the same. (True or False)
QUES. 6: Evaporation is is an example of a chemical change. (True or False)
QUES. 7: Salt or sugar dissolving in water is a physical change. (True or False)
Proc. 3. Mixtures of Liquids - A Simulated Oil Spill:
QUES. 8: The oil stays on the bottom of the water. (True or False) QUES. 9: The oil is more dense than the water. (True or False) QUES. 10: Solubility behavior and density behavior of oil and water is: a chemical or physical property ?
QUES. 11: a) Experimental Design: Devise at least two methods to remove the oil from the top of the water. Available devices are eye droppers to simulate a vacuum type device, paper towels, pieces of cotton balls, detergent, anything else that you can think of. State the hypothesis involved in each method or why you think it will work. Describe the actual experimental method that you used to remove the oil. What were the observations and results of your attempt to remove the oil? What were the conclusions about the usefulness of the method and relate back to the original hypotheis?
Repeat this cycle of hypothesis, method, results, conclusion on a second method. Compare the two methods for effectiveness. b) Would the methods that you used to clean up an oil spill have any applicability on a large body of water such as a river or ocean? You would need to think in terms of scale up. Explain.
PART 3. Chemical Reactions (4 points)
****All Data for Part 3 is given online**** ****You do not actually have to complete these procedures. Dr. Ophardt did them for you and took pictures of the results. You should read the procedures to see what was done, record the data, and answer the questions.*****
Procedure 1: Which metals react with Acids?
INTRODUCTION:
Did you know that pennies come in two varieties? Pennies minted before 1982 are made entirely from the metal element called copper. Pennies minted after 1982 contain a core made from the metal element zinc and the outer layer is made of copper. In this experiment, you will discover the chemical properties of zinc and copper metals, with hydrochloric, HCl, from Sno Bol toilet bowl cleaner.
1. A wire cutter type pliers or an old scissors was used to make five or six very thin cuts on the edges of a 1983 (or newer) penny. The cuts should expose a silvery metal which is zinc beneath the copper layer.
2. A cup was half filled with Sno Bol toilet bowl cleaner any other toilet bowl cleaner, in the lab 6M HCl can be used which contains hydrochloric acid. Next the penny is placed in the cup containing the Sno Bol toilet bowl cleaner.
3. Make and record observations during the first few minutes. Look for bubbles of hydrogen gas coming from the edges of the penny. This chemical reaction of the acid with the penny takes several days to complete.
QUES. 12: Which metal copper or zinc reacts with the hydrochloric acid?
QUES. 13: Which metal copper or zinc does not react with the hydrochloric acid?
This shows that metals may have different chemical properties towards the acids.
QUES. 14: What is the name of the element in the gas bubbles? Oxygen, Hydrogen, Chlorine
Explanation:
These observations are an example of how reactions show chemical properties. Various elements in the original substances undergo a chemical reaction where elements in compounds rearrange and change "forms" - metals into ions; and ions into the element form.
The outside coating of copper metal does not react with hydrochloric acid, HCl, in the toilet bowl cleaner., therefore the chemical proterty of copper toward hydrocloric acid is that copper DOES NOT react. The zinc metal core does react with the acid, hydrogen ions, H+, to produce zinc ions, chloride ions, (which are invisible in the water) and hydrogen gas bubbles (which escape into the air). The element zinc metal turns into soluble zinc ions, therefore the chemical property of zinc is that it DOES react with hydrochloric acid. The final result is a "hollow" penny. Two elements change form: zinc metal changes to zinc ions and hydrogen ions change into the diatomic hydrogen gas form.
Reactions:
Cu metal + HCl ===> No reaction
Zn metal + 2 HCl ===> Zn+2 ions + 2 Cl- ions + H2 gas
Procedure 2: Reaction of Zinc and Iodine
The reaction in this case is between two elements, zinc metal and iodine solid element. Both look sort of grayish in the photo. The reaction is started between the dry powders by adding a few drops of water. The reaction occurs as a combination reaction between the two elements to produce a single compound. During the reaction zinc metal gives two electrons to two iodine atoms to produce zinc +2 ions and two iodide -1 ions.
The reaction is: Zn metal + I2 ----> ZnI2
The reaction between the two elements to produce zinc iodide is very exothermic. Some of the unreacted iodine element solid is heated to a gaseous iodine which is purple in color.
QUES. 15: A molecule is ONLY defined as the simplest part of a compound with two or more different atoms. (True or False)
QUES. 16: For an exothermic reaction, heat is given off in the process. (True or False)
QUES. 17: The fact that unreacted iodine changes to gaseous iodine is a: chemical or physical change?
Procedure 3: Reaction of Efferdent and Alka-Seltzer with Water
The reactions in both of the above cases start when a solid tablet is dropped into water. The chemicals in dry solid form must dissolve in the water before a reaction may take place. In both cases gas bubbles are observed. A flaming or glowing splint is used to test for the identity of the gases.
Alka-Seltzer: (Baking soda or sodium bicarbonate) NaHCO3 + Citric acid ---> CO2 + H2O + Sodium Citrate Efferdent: (sodium perborate - a source of hydrogen peroxide) = H2O2 + catalyst ---> O2 + H2O
QUES. 18: First, define chemical property. Then use this definition to describe the difference in behavior toward the flaming splint for both gases in the above examples. State the chemical property of both oxygen and carbon dioxide toward the flaming splint similar to the statement about copper and zinc chemical properties stated in Procedure 1 above.
QUES. 19: Graphic of Baking Powder with Water - Revisited
Based upon the observations in the graphic, do you think that putting baking powder in water represents a physical or chemical change? Explain your answer.